Why Is A Mouse When It Spins?

For those unenlightened people. It goes like this.
Q  Why is amouse when it spins?
A  The higher it goes the fewer
This relates to the old days of the steam engine. The mouse was a small mechanical device fitted to the steam engine to regulate the speed of the engine (revs). The mouse had two small spheres which rotate and slide up and down to regulate the speed. When the spheres were high the res were low and vice verca. Thats the answer ... Suck it up.

I understand the whole...The mouse's name is Why

but the 2nd bit still perplexes me

But I beg of someone to tell me...is there actually a thing that is funny here or is the lack of there being something funny here the funny part?

Like....
Q:   What is the bowl of who's a camel?
A:   13 candles please

Am I a comedy genius or missing the point?

Because the higher it jumps the fewer. The question 'Why is a mouse when it spins' was first pondered by Raymond Zimbler back in the 1950s. His answer that the higher it jumps the fewer has been unchallenged ever since. A truly clever man.

The higher the fewer

I can not understand you

Because the higher it goes, the fewer.